when i try to access element:
browser.element('.object{ media }');
I get the following error message:
Error: Argument was an invalid selector (e.g. XPath/CSS).
at element(".object{ media }") - index.js:312:3
Is it possible to access elements by class name including curly brackets?
As per your question and your code trials to access desired element with classname containing curly brackets i.e. {} you can use the following solution:
XPath:
"//*[#class=\"object{ media }\"]"
Following what #DebanjanB said,
You can use something called Regular Expressions to sort issues like this out, what Debanjan has shown you is known as this.
Regular Expressions Guide
It would be useful if you read through a guide so you fully understand the code you are putting into your project, this will allow you to make better use of it later on in your testing.
All the best,
Jack
Related
I am working with MRJob through python and when I try to create a class, I get a synthax error. It's highlighting the colon. What am I missing? Here is my code:
class Bacon_count(MRJob):
You are defining an empty class, but in an unproper way. In Python an empty class should contain a pass statement, in your case:
class Bacon_count(MRJob):
pass
Also, take into account how to define single class methods in multiple cells, if that's what you are trying to do, as it is discussed here.
Is it possible to search elements usign regular expressions in locators.
The following works
set login [$window element by_class_name "frost-button"]
But the following doesn't work.
set login [$window element by_class_name "*button"]
No, you can't. When you call something like "by_class_name", the program will try to find element(s) that match the class name exactly that you pass as paramether.
So, if you try to search a class that contains a string, you need to use xpath or cssselector, but without using regex as well.
in Cssselector, the selector is this way:
*[class*='button']
Also, in Xpath is this way:
//*[contains(#class, 'button')]
i think to convert it into a tcl string you need to insert some slashes in the string. As i don't know the tcl, better I don't try.
Is there a way to pass the path to a simplexml node as a variable?
This is what I tried:
//set the path to the node in a variable
$comp = 'component->structuredBody->component';
echo count($xml->component->structuredBody->component); //=== 13
echo count($xml->$comp); //===0
echo count($xml->{$comp});//===0
What you need is XPath, and more specifically SimpleXML's xpath() method. Instead of traversing using PHP's -> operator, you would traverse using XPath's / operator, but otherwise, could achieve exactly the effect you wanted:
$comp = 'component[1]/structuredBody[1]/component';
echo count( $xml->xpath($comp) );
You might think that this could be simplified to 'component/structuredBody/component', but that would find all possible paths matching the expression - that is if there are multiple structuredBody elements, it will search all of them. That might actually be useful, but it is not equivalent to $xml->component->structuredBody->component, which is actually shorthand for $xml->component[0]->structuredBody[0]->component.
A few things to note:
Unlike most operations with SimpleXML, the result is an array, not another SimpleXML object (think of it as a set of search results). It is therefore vital that you check it is not empty before accessing element 0 as an object.
As you can see in the example above, XPath counts from 1, not 0. I don't know why, but it's caught me out before, so I thought I'd warn you.
The library SimpleXML is built on supports only XPath 1.0;
examples you see online for XPath 2.0 may not work.
XPath 1.0 has no notion of a "default namespace", and SimpleXML doesn't automatically register namespace prefixes for use in XPath, so if you're working with namespaces, you need to use registerXPathNamespace().
I have been using different forms of Mule's Expression language.
I couldn't figure out the difference between
#[flowVars.myVariable]
and
#[flowVars['myVariable']]
They both give the result when there is a variable. But why do they behave differently when the variable is not present?
Like if the variable being called is not available, then the first expression would result in a exception. Whereas the second expression just gives out a warning or prints out as is, if in a logger message.
Why is this difference?
Also when going through the documentation for Mule 3.6 I found that the second expression is not longer shown in the documentation.
Is the expression #[flowVars['myVariable']] being deprecated?
The difference comes from the way MVEL deals with these two different ways of accessing map entries.
#[flowVars['myVariable']] is equivalent to flowVars.get('myVariable'), which does not fail if the flowVars map does not contain the 'myVariable' entry,
#[flowVars.myVariable] treats the flowVars map as a virtual object, leading to an exception if the 'myVariable' entry is missing because in this case it doesn't resolve to a map get but instead to directly using an object member (either a field or a method), which must exist before being accessed.
I don't think #[flowVars['myVariable']] could be deprecated since it's a core feature provided by MVEL.
Reference: http://mvel.codehaus.org/MVEL+2.0+Property+Navigation#MVEL2.0PropertyNavigation-MapAccess
David has given a nice explanation around your question. To extend that explanation I would just like to add that you can use #[flowVars.?myVariable] to make your code null safe. This is equivalent to #[flowVars['myVariable']].
Regarding #[header:originalFilename], as David said this is not MEL. You can get a list of non-mel expressions which are commonly used in Mule applications in the following link.
http://www.mulesoft.org/documentation/display/current/Non-MEL+Expressions+Configuration+Reference
Aside from getting any real work done, I have an itch. My itch is to write a view engine that closely mimics a template system from another language (Template Toolkit/Perl). This is one of those if I had time/do it to learn something new kind of projects.
I've spent time looking at CoCo/R and ANTLR, and honestly, it makes my brain hurt, but some of CoCo/R is sinking in. Unfortunately, most of the examples are about creating a compiler that reads source code, but none seem to cover how to create a processor for templates.
Yes, those are the same thing, but I can't wrap my head around how to define the language for templates where most of the source is the html, rather than actual code being parsed and run.
Are there any good beginner resources out there for this kind of thing? I've taken a ganer at Spark, which didn't appear to have the grammar in the repo.
Maybe that is overkill, and one could just test-replace template syntax with c# in the file and compile it. http://msdn.microsoft.com/en-us/magazine/cc136756.aspx#S2
If you were in my shoes and weren't a language creating expert, where would you start?
The Spark grammar is implemented with a kind-of-fluent domain specific language.
It's declared in a few layers. The rules which recognize the html syntax are declared in MarkupGrammar.cs - those are based on grammar rules copied directly from the xml spec.
The markup rules refer to a limited subset of csharp syntax rules declared in CodeGrammar.cs - those are a subset because Spark only needs to recognize enough csharp to adjust single-quotes around strings to double-quotes, match curley braces, etc.
The individual rules themselves are of type ParseAction<TValue> delegate which accept a Position and return a ParseResult. The ParseResult is a simple class which contains the TValue data item parsed by the action and a new Position instance which has been advanced past the content which produced the TValue.
That isn't very useful on it's own until you introduce a small number of operators, as described in Parsing expression grammar, which can combine single parse actions to build very detailed and robust expressions about the shape of different syntax constructs.
The technique of using a delegate as a parse action came from a Luke H's blog post Monadic Parser Combinators using C# 3.0. I also wrote a post about Creating a Domain Specific Language for Parsing.
It's also entirely possible, if you like, to reference the Spark.dll assembly and inherit a class from the base CharGrammar to create an entirely new grammar for a particular syntax. It's probably the quickest way to start experimenting with this technique, and an example of that can be found in CharGrammarTester.cs.
Step 1. Use regular expressions (regexp substitution) to split your input template string to a token list, for example, split
hel<b>lo[if foo]bar is [bar].[else]baz[end]world</b>!
to
write('hel<b>lo')
if('foo')
write('bar is')
substitute('bar')
write('.')
else()
write('baz')
end()
write('world</b>!')
Step 2. Convert your token list to a syntax tree:
* Sequence
** Write
*** ('hel<b>lo')
** If
*** ('foo')
*** Sequence
**** Write
***** ('bar is')
**** Substitute
***** ('bar')
**** Write
***** ('.')
*** Write
**** ('baz')
** Write
*** ('world</b>!')
class Instruction {
}
class Write : Instruction {
string text;
}
class Substitute : Instruction {
string varname;
}
class Sequence : Instruction {
Instruction[] items;
}
class If : Instruction {
string condition;
Instruction then;
Instruction else;
}
Step 3. Write a recursive function (called the interpreter), which can walk your tree and execute the instructions there.
Another, alternative approach (instead of steps 1--3) if your language supports eval() (such as Perl, Python, Ruby): use a regexp substitution to convert the template to an eval()-able string in the host language, and run eval() to instantiate the template.
There are sooo many thing to do. But it does work for on simple GET statement plus a test. That's a start.
http://github.com/claco/tt.net/
In the end, I already had too much time in ANTLR to give loudejs' method a go. I wanted to spend a little more time on the whole process rather than the parser/lexer. Maybe in version 2 I can have a go at the Spark way when my brain understands things a little more.
Vici Parser (formerly known as LazyParser.NET) is an open-source tokenizer/template parser/expression parser which can help you get started.
If it's not what you're looking for, then you may get some ideas by looking at the source code.